It is desirable to be able to monitor, in some cases,the luminosity of a source of light, for example in a dining room during tea time.
It is known to provide pivotal louver means, surrounding the light bulb, for monitoring the desired amount of light allowed to escape therethrough. Various models thereof have already been proposed, e.g. U.S. Pat. Nos. 3,275,820 for automobile headlights, or U.S. Pat. No. 3,598,988 for a lamp hanging from a ceiling chain. One drawback of such light-intensity monitoring means is the means to actuate pivotal action of the louvers , said actuating means often being inefficient and/or structurally complex.